Fire grate system for a low-emission outdoor fire ring

ABSTRACT

The present invention is directed to several embodiments or variations of a fire grate system for a low-emission outdoor fire pit or fire ring. Several of these variations use the same fundamental fire grate framework within the system and are adapted burn liquefied petroleum gas (LPG), a common example of which is propane. A first embodiment of the invention may simulate a wood fire without burning wood by securely attaching artificial ceramic (or similarly constructed) fire logs to a LPG gas-burning fire grate framework. A second, alternative embodiment of the present invention is a gas/wood hybrid system and that uses LPG fuel to reduce emissions from a wood fire.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to, and the benefit of, U.S. Provisional Application Ser. No. 61/916,951 entitled “LOW-EMISSION OUTDOOR PUBLIC BEACH-TYPE FIRE RING AND RETROFIT DEVICE FOR OUTDOOR PUBLIC BEACH-TYPE FIRE RING,” filed on Dec. 17, 2013, the disclosure of which is herein incorporated by reference in its entirety.

STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT

Not Applicable

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

The present disclosure relates generally to fire pits, such as fire pits for recreation at public beaches. More particularly, the present disclosure relates to an apparatus for improving efficiency of an outdoor public beach-type fire ring in relation to reduction in harmful emissions.

2. Discussion of the Related Art

A city's open space areas, such as beaches and parks, may be protected and preserved as natural resources, visual amenities, and/or recreational opportunities. Recreational fire rings and portable fire pits may be permitted uses in a city's open space areas, under locally administered laws and ordinances.

Visitors to public beaches and parks may find a change in the fuels that can be used for the fire rings. This comes about because of renewed interest in reducing harmful pollution including PM_(2.5), carbon monoxide (CO), toxic air pollutants (e.g., benzene and formaldehyde), and climate gases (e.g. methane and black carbon) from burning wood and the promulgation of new regulations to protect and improve air quality. In some regions, if a city's fire rings are 700 feet or less from residential areas, then the fuel source can only be charcoal unless the rings are spaced out at least 100 feet apart from each other.

The health benefits associated with reducing PM_(2.5) emissions, including wood smoke, are widely accepted as significant. According to the U.S. Environmental Protection Agency (EPA), studies show that exposure to PM_(2.5) can cause premature death and harmful effects on the cardiovascular system (the heart, blood, and blood vessels). Particle pollution exposure is also linked to a variety of other public health problems, including respiratory diseases.

There is a need for apparatus for improving efficiency of an outdoor public beach-type fire ring in relation to reduction in harmful emissions. The present invention, as will be described in more detail below, address this particular need in the art.

BRIEF SUMMARY OF THE INVENTION

According to an aspect of the present disclosure, there is provided several embodiments or variations of a fire grate system for a low-emission outdoor fire pit or fire ring. Several of these variations use the same fundamental fire grate framework within the system and are adapted burn liquefied petroleum gas (LPG), a common example of which is propane. A first embodiment of the invention may simulate a wood fire without burning wood by securely attaching artificial ceramic (or similarly constructed) fire logs to a LPG gas-burning fire grate framework. Ceramic fire logs have traditionally been used in residential gas fireplaces and, within the context of the present invention, will require appropriate sizing and the selection of those fire logs that are robustly constructed to provide a simulated wood fire in an outdoor public setting.

A second, alternative embodiment of the present invention is a gas/wood hybrid system and that uses LPG fuel to reduce emissions from a wood fire. Wood fires are preferred by many users and the gas/wood hybrid variant constituting the second embodiment is for use in areas where wood fuel is allowable.

A conversion between the first and second embodiments is envisioned in accordance with the present invention, and may be simply accomplished by the adjustment of gas flow and the addition or removal of the ceramic fire logs to/from the fire grate framework. This convertibility will allow responsiveness to possible changes in future regulations and will provide for devices with similar appearances on the beach. Further, both embodiments will allow traditional open fire cooking activities such as hot dogs and marshmallows. In fact, the cooking experience could be enhanced with the placement of holders for cooking forks, sticks or grills on the fire grate framework.

It is well established that the use of gaseous hydrocarbon fuels such as natural gas or LPG is a well-recognized approach for the oxidation of products of incomplete combustion (PIC) in industrial applications and is often the primary feature of industrial after burner emission control. The complete oxidation of PIC forms carbon dioxide and water. As well as for industrial air pollutant sources, the oxidation of PIC from the combustion of biomass fuels in residential fireplaces and woodstoves has also been accomplished by the supplemental use of natural gas or LPG combustion. Along these lines, certain embodiments of the present invention include structural modalities to facilitate the introduction of air to a secondary combustion zone and the combustion of natural gas or LPG to oxidize PIC and reduce air emissions. The combustion environment of a fire ring is similar to a simple fireplace and particulate reduction may be obtained with the presently-disclosed fire grate system for a low-emission outdoor fire ring. In this regard, the introduction of air to a secondary combustion zone enhances the oxidation of PIC.

One or more components associated with LPG storage, flow, regulation, and combustion as integrated into the fire grate system of the present invention may be “off-the-shelf” components primarily designed for use with residential factory manufactured gas fireplaces, residential gas fire log sets, residential gas stoves, residential gas barbecues/smokers, residential fireplace gas log lighters, or camp stoves. Further, the fire grate framework of the fire grate system of the present invention may be fabricated from the same materials (e.g., 330 stainless steel) and possess one or more of the structural and/or functional attributes of Applicant's current hybrid clean burn system for fireplaces, a more detailed description of which is disclosed in Applicant's U.S. Design Pat. No. D635,657, U.S. Patent Application Publication No. 2011/0005511, U.S. Patent Application Publication No. 2012/0192855, and U.S. Patent Application Publication No. 2012/0204858, the disclosures of which are herein incorporated by reference in their entireties. The preferred use of stainless steel as a construction material for the presently-disclosed fire grate framework makes it resistant to corrosion from sea salt, mineral acids produced from the possible inappropriate burning of plastics or other trash, and abrasion from wind-blown silica sand.

The goals of air emission control from outdoor fire rings outfitted with the fire grate system of the present invention include the reduction in PM_(2.5) and PM₁₀, though there are also other air quality benefits from the present design. Volatile organic compounds (VOC) and carbon monoxide emissions will also be reduced significantly by both of the proposed embodiments/variations of the present invention. Many of the compounds making up VOC are photochemically active and as such participate in ozone formation. Many of the compounds making up VOC from biomass combustion are toxic, mutagenic or carcinogenic, such as formaldehyde, acetaldehyde, and benzene. About one half of the VOC from biomass combustion is made up of methane, a potent greenhouse gas. While not a VOC, the toxicity of carbon monoxide is also well known. As with products of incomplete combustion that make up particles, the use of LPG combustion and secondary combustion in parallel with a wood fire oxidizes VOC into carbon dioxide and water. Similarly, carbon dioxide is produced from carbon monoxide. In addition to the destruction of VOC and carbon monoxide emitted from wood in the LPG/wood hybrid variation, the use of LPG alone without wood in that variation simply will produce much less of these emissions than burning wood.

In addition to the direct oxidation of particles during a wood fire, the use of supplemental LPG combustion as facilitated by the structural features of certain embodiments of the fire grate system of the present invention reduces the duration of the start-up phase of the fire when combustion conditions are inefficient. Research with residential wood stoves has shown that a disproportionate amount of air emission occur during the “kindling” phase of the fire. In addition, the use of LPG to start the fire reduces the need for starter materials which are often not clean burning. These often include plastics, household waste paper, miscellaneous biomass materials, etc. By using LPG, part of the energy, part of the visual flame production and part of the radiant heat normally produced by wood in a traditional wood fire is replaced by LPG which is inherently cleaner burning. Consequently, a recreational experience of wood flames, radiant heat, and wood smoke aroma can be produced and, as a result burning less wood, harmful emissions can be reduced using the fire grate system of the present invention.

The present invention is best understood by reference to the following detailed description when read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Objects and features of the presently-disclosed fire grate system and a gas delivery apparatus for a low-emission outdoor fire pit will become apparent to those of ordinary skill in the art when descriptions of various embodiments thereof are read with reference to the accompanying drawings, of which:

FIG. 1 is a perspective view of a fire grate system for a low-emission outdoor fire pit in accordance with an embodiment of the present disclosure;

FIG. 2 is a perspective view of a low-emission outdoor fire pit including a stationary-type fire ring with the fire grate system of FIG. 1 in accordance with an embodiment of the present disclosure;

FIG. 3 is a perspective view of a low-emission outdoor fire pit including a fire ring with the fire grate system of FIG. 1 in accordance with an embodiment of the present disclosure;

FIG. 4 is a perspective view of a collapsible fire grate system for a low-emission outdoor fire pit, in an first configuration, in accordance with an embodiment of the present disclosure;

FIG. 5 is a perspective view of the collapsible fire grate system of FIG. 4, in a second configuration, in accordance with an embodiment of the present disclosure;

FIG. 6 is a perspective view of the collapsible fire grate system of FIG. 4, in a third configuration, in accordance with an embodiment of the present disclosure; and

FIG. 7 is a perspective view of a gas delivery apparatus for a low-emission outdoor fire pit in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiments of a fire grate system and a gas delivery apparatus for a low-emission outdoor fire ring or fire pit are described with reference to the accompanying drawings. Like reference numerals may refer to similar or identical elements throughout the description of the figures.

This description may use the phrases “in an embodiment,” “in embodiments,” “in some embodiments,” or “in other embodiments,” which may each refer to one or more of the same or different embodiments in accordance with the present disclosure.

Referring now to FIG. 1, the fire grate system 100 for a low-emission outdoor fire pit is shown. The predominant structural feature of the fire grate system 100 is a fire grate framework 101, shown with particularity in FIG. 1. The fire grate framework 101 may be made from any suitable material of appropriate temperature and chemical resistance characteristic, e.g., iron, steel, aluminum, ceramics, etc.

The fire grate framework 101 includes a grate structure 70 configured to provide a cradle for supporting wood (e.g., burning logs) or other material, a gas manifold 50 configured to provide dual gas flow paths, and an air outlet manifold 10. In some embodiments, as shown for example in FIG. 1, the air outlet manifold 10 is configured to be removably coupleable to the gas manifold 50.

The grate structure 70 generally includes a configuration of frames (e.g., three frames 71, 73, 75 shown in FIG. 1) and a configuration of cross bars (e.g., four cross bars 72, 74, 76, 78 shown in FIG. 1) arranged to collectively define a support area “A” configured to receive material, such as combustible material (e.g., wood) or non-combustible material (e.g., ceramic fire logs) thereon. The support area “A” may have an outer perimeter that is generally rectangular in shape. It is to be understood that any suitable length “L₁” and any suitable width “W₁” may be utilized, e.g., depending on the configuration of a fire ring (e.g., fire ring 200 shown in FIG. 2). In other embodiments, the frames and the cross bars may be arranged in a variety of grate structure configurations, e.g., circular shapes, oblong shapes, angular shapes, curve segments, curvilinear shapes, etc.

When viewed from the perspective shown in FIG. 1, the gas manifold 50 includes an upper manifold tube 20, a lower manifold tube 30, and a connector tube 40 disposed in fluid communication between the upper manifold tube 20 and the lower manifold tube 30. The upper and lower manifold tubes are juxtaposed, extending in spaced, generally parallel relation to each other. In some embodiments, the upper manifold tube 20, the lower manifold tube 30, and the connector tube 40 may be integrally formed as a single piece of tubing. A longitudinally-extending gas delivery conduit defined by the upper manifold tube 20 and longitudinally extending gas delivery conduit defined by the lower manifold tube 30 are disposed in fluid communication with each other via the connector tube 40, which itself fluidly communicates with a gas inlet tube 42 protruding from the approximate center thereof.

The upper manifold tube 20 defines a plurality of gas distribution apertures 21 in fluid communication with the gas delivery conduit therethrough. Similarly, the lower manifold tube 30 defines a plurality of gas distribution apertures 31 in fluid communication with the gas delivery conduit therethrough. Although a single row of gas distribution apertures 21 associated with the upper manifold tube 20 and a single row of gas distribution apertures 31 associated with the lower manifold tube 30 are shown in FIG. 1, a variety of row-column aperture patterns (or other aperture patterns) may be utilized. The size and shape of the gas distribution apertures 21 and the gas distribution apertures 31 may be varied from the configuration shown in FIG. 1.

The air outlet manifold 10 includes an air outlet tube 12 configured to be positioned in a laterally offset relationship from the upper manifold tube 20. The air outlet tube 12 defines a longitudinally extending air delivery conduit therethrough and a plurality of air distribution apertures 11 in communication with the air delivery conduit. One or more air intake tubes (e.g., three air intake tubes 14 a, 14 b, 14 c) may be disposed in fluid communication with the air delivery conduit. In the embodiment shown in FIG. 1, the air intake tubes 14 a, 14 b, 14 c are disposed in a side-by-side relationship, and extend in spaced, generally parallel relation to each other. In some embodiments, as shown for example in FIG. 1, the air intake tubes 14 a, 14 b, 14 c each include an upper coupling member 16 a, 16 b, 16 c, respectively, configured to releasably engage the upper manifold tube 20, and a lower coupling member 18 a, 18 b, 18 c, respectively, configured to releasably engage the lower manifold tube 30. The lower ends of the air intake tubes 14 a, 14 b, 14 c each further define an air inlet opening. A person of ordinary skill in the art will appreciate that the shape and length of the air intake tubes 14 a, 14 b, 14 c and the location of the air inlet openings (e.g., in relation to the grate structure 70) may be varied from the configuration shown in FIG. 1. For example, one or more of the air intake tubes 14 a, 14 b, 14 c may be configured to place the air inlet opening(s) outside of the perimeter of the grate structure 70.

When viewed from the perspective shown in FIG. 1, the releasable attachment of the air outlet manifold 10 to the gas manifold 50 through the use of the upper coupling members 16 a, 16 b, 16 c and the lower coupling members 18 a, 18 b, 18 c causes the air outlet tube 12 of air outlet manifold 10 to assume an orientation wherein it extends in spaced, generally parallel relation to, but is further elevated above, the upper manifold tube 20 of the gas manifold 50. At the same time, the air inlet openings of the air intake tubes 14 a, 14 b, 14 c are disposed below the lower manifold tube 30 of the gas manifold 50. The significance of these relative orientations as it pertains to the overall functionality of the fire grate system 100 will be discussed in more detail below.

FIG. 2 shows a fire pit including the fire grate system 100 as associated with a stationary-type fire ring 200. Fire ring 200 includes an outer wall 202 and an inner wall 204 defining a cavity therein. A gas feed path 210 constituting part of the fire grate system 100 is provided to supply gas to the inlet tube 42 of the fire grate framework 101 of the fire grate system 100. The gas feed path 210 includes a suitable conduit (e.g., metal piping or tubing, flexible metal tubing, stainless steel hose), and may include fittings. An on/off valve 215 is integrated into the gas feed path 210 to facilitate hook up with a suitable natural gas or LPG source, such as a propane tank. The valve 215 may have built-in safety devices, e.g., to prevent gas leakage and moisture leakage into the gas feed path 210. The valve 215 includes a lever arm 217 selectively movable between open and closed positions. Assuming the gas feed path 210 is operatively coupled to a propane tank, the actuation of the lever arm 217 to its open position allows for the flow of propane from the tank (which may be outfitted with its own on/off valve) into the gas feed path 210 via the valve 215. Conversely, the actuation of the lever arm 217 to its closed position effectively blocks the flow of propane from the tank into the gas feed path 210.

Having thus described the structural attributes of the fire grate system 100, and in particular the fire grate framework 101 thereof, the functional attributes of the fire grate system 100 as integrated into the fire ring 200 will now be described with specific reference to FIG. 2. In greater detail, with the fire grate framework 101 being suitably positioned within the cavity of the fire ring 200, ceramic fire logs or, optionally, conventional wood fire logs are positioned upon the support area “A” of the grate structure 70. If the fire ring 200 is intended to be used solely in applications or environments wherein wood is not burned therein, it is contemplated that the ceramic fire logs may be pertinently attached to the grate structure 70 within the support area “A” thereof, thus eliminating the separate step of attaching the same to the grate structure 70.

With the ceramic fire logs or wood fire logs in place within the support area “A” of the grate structure 70, the gas feed path is operatively coupled to, for example, a propane supply. The actuation of the lever arm 217 of the valve 215 to its open position facilitates the flow of propane to and into the gas manifold 50 via the gas feed path 210. As indicated above, it is contemplated that a suitable propane source, such as a conventional propane tank, will be fluidly coupled to the on/off valve 215 prior to the actuation of the lever arm 217 thereof from its closed to its open position. The propane gas entering the connector tube 40 of the gas manifold 50 is in turn channeled into each of the upper and lower manifold tubes 20, 30 of the gas manifold 50. The propane gas exiting the gas distribution apertures 21, 31 defined by respective ones of the upper and lower manifold tubes 20, 30 is ignited in a conventional manner thus resulting in continuous flame emanation from each of the upper and lower manifold tubes 20, 30, such flame emanation continuing until such time as the actuation lever 217 of the aforementioned on/off valve 215 is moved from its open to its closed position.

As will be recognized, due to principles of heat convection, over time, flame generation from the upper and lower manifold tubes 20, 30 of the gas manifold 50 will result in the temperature of the air proximate the air outlet tube 12 of the air outlet manifold 10 being substantially elevated beyond the temperature of the air proximate the air inlet openings defined by the air intake tubes 14 a, 14 b, 14 c of the air outlet manifold 10 which are well below the level of the air outlet tube 12. This temperature differential creates a chimney effect wherein air is circulated through the air outlet manifold 10 in the direction depicted by the arrows included in FIG. 1, the air entering the air inlet openings of the air intake tubes 14 a, 14 b, 14 c, and being dispensed or distributed from the distribution apertures 11 disposed within the air outlet tube 12. Considering the preferred spatial relationships between the air outlet manifold 10 and the gas manifold 50 as described above, the air emanating from the air outlet tube 12 of the air outlet manifold 10 is introduced into a secondary combustion zone slightly elevated above the gas manifold 50 within the fire grate system 100, and hence a primary combustion zone defined by ignited gas flowing from the apertures 21, 31 of the upper and lower manifold tubes 20, 30 of the gas manifold 50. As described above, the introduction of air into this secondary combustion zone by virtue of the functionality of the air outlet manifold 10 works in concert with the propane combustion occurring at the upper and lower manifold tubes 20, 30 of the gas manifold 50 to facilitate the oxidation of products of incomplete combustion, thereby effectively reducing PIC air emissions.

Referring now to FIG. 3, there is shown a fire pit 300 which is a structural variant of the fire ring 200 shown in FIG. 2, and is also adapted to accommodate the fire grate system 100 of the present invention. The fire pit 300 includes a peripheral wall 310 which circumvents a floor, both the wall 310 and floor having generally circular configurations, and collectively defining a cavity. Disposed within the wall 310 is a multiplicity of openings 311 which each communicate with the cavity. As shown in FIG. 3, each of the openings 311 has a generally quadrangular configuration, though other shapes or arrangements of the openings 311 other than those shown in FIG. 3 are intended to be encompassed within the spirit and scope of the present invention. The wall 310 also includes a plurality of support legs 320 protruding from a common end thereof, the support legs 320 being adapted to maintain the cavity in an elevated orientation above an underlying support surface. The fire grate system 100, and in particular the fire grate framework 101 is accommodated within the interior cavity partially defined by the wall 310. The aforementioned gas feed path 10 is integrated into the wall 310 and or floor of the fire pit 300 and used to facilitate the hook up of the fire grate frame work 101 to a propane tank or other suitable combustible gas supply.

Referring now to FIGS. 4-6, there is shown a fire grate system 500 including a fire grate framework 501 which is a collapsible variant of the above-described fire grate framework 101 integrated into the fire grate system 100 Like the above-described fire grate framework 101, the fire grate framework 501 may be made from any suitable material of appropriate temperature and chemical resistance characteristic.

The fire grate framework 501 includes a grate structure 570, the structural attributes minor those of the grate structure 70 described above in relation to the fire grate system 100. In this regard, the grate structure generally includes a configuration of frames (e.g., three frames 571, 573, 575) which each have a generally sigma-like configuration, defining a central recessed portion when observed from a horizontal perspective. These frames 571, 573, 575 and a configuration of cross bars within the grate structure 570 are, as in the grate structure 70, configured to provide a cradle for supporting wood, ceramic fire logs, or other material. In addition to the grate structure 570, the fire grate framework 501 includes a gas manifold 550 configured to provide dual gas flow paths, and an air outlet manifold 510.

When viewed from the perspective shown in FIGS. 4-6, the gas manifold 550 includes an upper manifold tube 520, a lower manifold tube 530, and an arcuate connector tube 540 which is integrally connected to and fluidly couples the upper and lower manifold tubes 520, 530 to each other. The upper and lower manifold tubes 520, 530 are juxtaposed, extending in spaced, generally parallel relation to each other. It is contemplated that the upper and lower manifold tubes 520, 530 and intervening connector tube 540 will be integrally formed as a single piece of tubing, suitably bent to assume the overall structure profile (i.e., a generally U-shaped configuration) as shown in FIGS. 4-6. A longitudinally extending gas delivery conduit defined by the upper manifold tube 520 and a longitudinally extending gas delivery conduit defined by the lower manifold tube 530 are disposed in fluid communication with each other via the connector tube 540.

The upper manifold tube 520 defines a plurality of gas distribution apertures 521 in fluid communication with the gas delivery conduit therethrough. Similarly, the lower manifold tube 530 defines a plurality of gas distribution apertures 531 in fluid communication with the gas delivery conduit therethrough. Although a single row of gas distribution apertures 521 associated with the upper manifold tube 520 and a single row of gas distribution apertures 531 associated with the lower manifold tube 530 are shown in FIGS. 4-6, a variety of row-column aperture patterns (or other aperture patterns) may be utilized. In addition, the size and shape of the gas distribution apertures 521, 531 may be varied from the configuration shown in FIGS. 4-6.

In the fire grate framework 501, it is contemplated that the gas manifold 550, and in particular the lower manifold tube 530 thereof, will be rotatably connected to the grate structure 570. In greater detail, it is contemplated that the lower manifold tube 530 will be rotatably connected to the aforementioned central recessed portion of each of the three frames 571, 573, 575 included in the grate structure 570. As is apparent from FIGS. 5 and 6, the distal end of the lower manifold tube 530 protrudes from the frame 571, and may be used as a gas inlet to facilitate the introduction of natural gas or an LPG such as propane into the gas manifold 550. The advantages attendant to the rotatable connection of the gas manifold 550 to the grate structure 570 will be described in more detail below.

The air outlet manifold 510 integrated into the fire grate framework 501 of the fire grate system 500 includes an air outlet tube 512 configured to be positioned in a laterally offset relationship from the upper manifold tube 520. The air outlet tube 512 defines a longitudinally extending air delivery conduit therethrough and a plurality of air distribution apertures 511 in communication with the air delivery conduit. One or more air intake tubes (e.g., two air intake tubes 514 a, 514 b) may be disposed in fluid communication with the air delivery conduit. In the embodiment shown in FIGS. 4-6, the air intake tubes 514 a, 514 b extend and space, generally parallel relation to each other, and in a common direction from respective ones of the opposed end portions of the air outlet tube 512. The air intake tube 514 a is outfitted with an upper coupling member 517 a and a lower coupling member 519 a which have identical, generally quadrangular configurations. The upper coupling member 517 a accommodates the upper manifold tube 520 of the gas manifold 550 which is extended therethrough. Similarly, the lower coupling member 519 a accommodates the lower manifold tube 530 which is extended therethrough. Similar to the air intake tube 514 a, the air intake tube 514 b is outfitted with an upper coupling member 517 b and a lower coupling member 519 b, the structural attributes of which mirror those of the upper and lower coupling members 517 a, 519 a. Like the upper and lower coupling members 517 a, 519 a of the air intake tube 514 a, the upper and lower coupling members 517 b, 519 b of the air intake tube 514 b accommodate the upper and lower manifold tubes 520, 530 respectively, which are also each extended therethrough. The lower ends of the air intake tubes 514 a, 514 b each further define an air inlet opening.

In the fire grate framework 501, the grate structure 570 is outfitted with a pin P which protrudes laterally outward from the frame 571 thereof in the manner shown in FIG. 4. The pin P is selectively insertable into and removable from within a complimentary notch N disposed within the lower coupling member 519 b of the air intake tube 514 b. The receipt of the pin P into the notch N is effective to maintain the air outlet manifold 510, and hence the gas manifold 550, in the generally vertical orientation shown in FIG. 4. The selective removal of the pin P from within the notch N as occurs when the air outlet manifold 510 is lifted or elevated relative to the gas manifold 550 in the manner shown in FIG. 5 allows the air outlet manifold 510 and gas manifold 550 to be concurrently rotated to a collapsed or stowed position shown in FIG. 6. As is apparent from FIG. 5, the elevation or lifting of the air outlet manifold 510 to facilitate the removal of the pin P from within the notch N results in the downward movement of the upper manifold tube 520 within the upper coupling members 517 a, 517 b through which it is extended in comparison to the orientation shown in FIG. 4. Similarly, the lower manifold tube 530 is caused to move downwardly within the lower coupling members 519 a, 519 b through which it is extended in comparison to the orientation shown in FIG. 4.

Subsequent to the air outlet manifold 510 being actuated in the manner shown in FIG. 5, as indicated above, the same along with the gas manifold 50 is capable of being rotated in a counter-clockwise direction as viewed from the perspective shown in FIGS. 4-6 to the generally horizontal, collapsed state shown in FIG. 6. The aforementioned rotatable coupling of the gas manifold 550 to the grate structure 570 allows it to be pivoted or rotated to the flattened or collapsed orientation, with the air outlet manifold 510 simultaneously being rotated to precisely the same orientation by virtue of its coupling to the gas manifold 550 via the upper and lower coupling members 517 a, 517 b, 519 a, 519 b. As further seen in FIGS. 4-6, the grate structure 570 is also preferably outfitted with at least one receptacle 577 which is operative to support the air intake tube 514 a, and hence the air outlet manifold 510 when it, along with the gas manifold 550, is actuated from its deployed or extended state shown in FIG. 4 to its stowed or collapsed state shown in FIG. 6. Those of ordinary skill in the art will recognize that the fire grate framework 501 and ancillary components such as the gas feed path 210 collectively defining the fire grate system 500 may themselves be integrated into structures such as the fire ring 200 and the fire pit 300 described above.

Referring now to FIG. 7, there is shown a fire grate system 700 including a fire grate framework 701 uniquely configured to accommodate wood arranged in a vertically oriented, tee-pee like configuration. The fire grate framework 701 includes a lower frame assembly 710 which is formed to have a generally hexagonal configuration. In greater detail, the lower frame assembly 710 comprises a plurality of tubular segments 712, several pairs of which are fluidly connected to each other in end-to-end fashion by intervening elbow connectors 714. Within the lower frame assembly 710, several pairs of the segments 712 are fluidly connected to each other in end-to-end fashion by intervening T-connectors 716. When viewed from the perspective shown in FIG. 7, three of these T-connectors 716 have a downwardly protruding branch which is operatively coupled to a corresponding support leg 718. The distal end of each support leg 718, which may be tubular, has an end cap 720 attached thereto. The support legs 718 (and hence the T-connectors 716 to which they are attached) are provided in a generally triangular arrangement, thus providing stable support to the lower frame assembly 710 while being operative maintain the same in an elevated orientation above an underlying support surface.

When also viewed from the perspective shown in FIG. 7, two of the T-connectors 716 have an upwardly protruding branch which is fluidly coupled to the bottom end of a respective one of a pair of identically configured, tubular riser members 722. Finally, one T-connector 716 has a lateral, outwardly protruding branch which defines a gas inlet.

In the fire grate framework 701, one of the riser members 722 is fluidly coupled to a first upper frame assembly 724. In greater detail, the first upper frame assembly 724 comprises a plurality of tubular segments 726, several pairs of which are fluidly connected to each other in end-to-end fashion by intervening elbow connectors 728. Within the first upper frame assembly 724, one of the segments 712 is also fluidly connected to a T-connector 730. When viewed from the perspective shown in FIG. 7, a downwardly protruding branch of such T-connector 730 is fluidly coupled to the top end of the corresponding riser member 722. Additionally, one of the horizontally extending branches of such T-connector 730 is enclosed by an end cap, as is the distal end of that segment 726 disposed furthest from the T-connector 730.

In addition, one of the riser members 722 is fluidly coupled to a second upper frame assembly 732. In greater detail, the second upper frame assembly 732 comprises a plurality of tubular segments 734, a pair of which is fluidly connected to each other in end-to-end fashion by an intervening elbow connector 736. Within the second upper frame assembly 732, a pair of the segments 734 is also fluidly connected to each other by an intervening T-connector 738. When viewed from the perspective shown in FIG. 7, a downwardly protruding branch of such T-connector 738 is fluidly coupled to the top end of the corresponding riser member 722. The distal ends of the segments 734 of the outermost pair thereof within the second upper frame assembly 732 are each enclosed by an end cap.

In the fire grate framework 701, each of the segments 712, 726, 734 is provided with a single row of gas distribution apertures 740. Within the lower frame assembly 710, the apertures 740 fluidly communicate with the gas delivery conduit collectively defined by the segments 712, elbow connectors 714 and T-connectors 716. Within the first upper frame assembly 724, the apertures 740 fluidly communicate with the gas delivery conduit collectively defined by the segments 726, elbow connectors 728 and T-connector 730. Within the second upper frame assembly 732, the apertures 740 fluidly communicate with the gas delivery conduit collectively defined by the segments 734, elbow connector 736 and T-connector 738. The size, shape and/or arrangement of the gas distribution apertures 740 may be varied from the configuration shown in FIG. 7. The gas delivery conduits of the first and second upper frame assemblies 724, 732 are placed into fluid communication with the gas delivery conduit of the lower frame assembly 710 by respective ones of the riser members 722, each of which is preferably devoid of any gas distribution apertures. The gas delivery conduit of the lower frame assembly 710 is itself capable of being placed into fluid communication with a combustible gas source via the aforementioned gas inlet defined by one of the T-connectors 716 of the lower frame assembly 710.

As indicated above, the structural attributes of the fire grate framework 701, and in particular the lower, first upper and second upper frame assemblies 710, 724. 732 thereof, make it uniquely suited to accommodate the wooden planks bundled in a tee-pee like arrangement. Additionally, those of ordinary skill in the art will recognize that the fire grate framework 701 may be outfitted with ancillary components such as the gas feed path 210 to collectively define the fire grate system 700. It is also contemplated that the fire grate system may be sized and configured in a manner which it allows it to be accommodated by, for example, the cavity of the above-described fire ring 200.

Although embodiments have been described in detail with reference to the accompanying drawings for the purpose of illustration and description, it is to be understood that the disclosed processes and apparatus are not to be construed as limited thereby. It will be apparent to those of ordinary skill in the art that various modifications to the foregoing embodiments may be made without departing from the scope of the disclosure. 

What is claimed is:
 1. A fire grate system for a low-emission outdoor fire ring, the fire grate system comprising: a grate structure; a gas manifold attached to the grate structure and fluidly connectible to a gas supply, the gas manifold having a plurality of gas distribution apertures disposed therein and operative to distribute gas flowing therethrough into a primary combustion zone; and an air outlet manifold cooperatively engaged to the gas manifold, the air outlet manifold having a plurality of air distribution apertures disposed therein and operative to distribute air flowing therethrough into a secondary combustion zone proximate the primary combustion zone.
 2. The fire grate system of claim 1, wherein the air outlet manifold is removably connected to the gas manifold.
 3. The fire grate system of claim 1 wherein the gas manifold is rotatably connected to the grate structure, and selectively movable between extended and collapsed positions relative thereto.
 4. The fire grate system of claim 1, further in combination with an annular fire ring structure defining a cavity, the fire grate system at least partially residing with the cavity.
 5. The fire grate system of claim 1, further in combination with a fire pit structure defining an elevated cavity, the fire grate system at least partially residing with the cavity.
 6. The fire grate system of claim 1, wherein the gas manifold comprises: an upper manifold tube; a lower manifold tube; and a connection tube extending between and fluidly connecting the upper and lower manifold tubes to each other.
 7. The fire grate system of claim 6 wherein the gas distribution apertures are disposed in only the upper and lower manifold tubes.
 8. The fire grate system of claim 7 wherein the upper and lower manifold tubes and intervening connection tube are integrally connected to each other.
 9. The fire grate system of claim 6 wherein the air outlet manifold comprises: an air outlet tube disposed proximate the upper manifold tube when the air outlet manifold is operatively coupled to the gas manifold; and at least one air intake tube fluidly connected to and protruding from the air outlet tube, the air intake tube defining an air inlet opening which is disposed proximate one side of the primary combustion zone opposite another side thereof which is proximate the secondary combustion zone.
 10. The fire grate system of claim 9 wherein the air distribution apertures are disposed in only the air outlet tube.
 11. The fire grate system of claim 9 wherein three air outlet tubes are fluidly connected to and protrude from the air outlet tube in a common direction and in equidistantly spaced, generally parallel relation to each other.
 12. The fire grate system of claim 9 wherein two air outlet tubes are fluidly connected to and protrude from the air outlet tube in a common direction and in spaced, generally parallel relation to each other.
 13. A fire grate system for a low-emission outdoor fire ring, the fire grate system comprising: a grate structure; a gas manifold rotatably connected to the grate structure and fluidly connectible to a gas supply, the gas manifold having a plurality of gas distribution apertures disposed therein and operative to distribute gas flowing therethrough into a primary combustion zone; and an air outlet manifold cooperatively engaged to the gas manifold and releasably engaged to the grate structure, the air outlet manifold having a plurality of air distribution apertures disposed therein; the gas and air outlet manifolds being selectively movable between extended and collapsed positions relative to the grate structure, with the air outlet manifold being operative to distribute air flowing therethrough into a secondary combustion zone proximate the primary combustion zone when both the gas and air outlet manifolds are in the extended position.
 14. The fire grate system of claim 13, further in combination with an annular fire ring structure defining a cavity, the fire grate system at least partially residing with the cavity.
 15. The fire grate system of claim 13, further in combination with a fire pit structure defining an elevated cavity, the fire grate system at least partially residing with the cavity.
 16. The fire grate system of claim 13, wherein the gas manifold comprises: an upper manifold tube; a lower manifold tube; and a connection tube extending between and fluidly connecting the upper and lower manifold tubes to each other.
 17. The fire grate system of claim 16 wherein the gas distribution apertures are disposed in only the upper and lower manifold tubes.
 18. The fire grate system of claim 17 wherein the upper and lower manifold tubes and intervening connection tube are integrally connected to each other.
 19. The fire grate system of claim 13 wherein the air outlet manifold comprises: an air outlet tube disposed proximate the upper manifold tube when the air outlet manifold is operatively coupled to the gas manifold; and at least one air intake tube fluidly connected to and protruding from the air outlet tube, the air intake tube defining an air inlet opening which is disposed proximate one side of the primary combustion zone opposite another side thereof which is proximate the secondary combustion zone.
 20. A fire grate system for a low-emission outdoor fire ring, the fire grate system comprising: a ring-like, lower frame assembly fluidly connectible to a gas supply, the lower frame assembly having a plurality of gas distribution apertures disposed therein, the ; a first upper frame assembly fluidly connected to and elevated above the lower frame assembly, the first upper frame assembly having a plurality of the gas distribution apertures disposed therein; and a second upper frame assembly fluidly connected to and elevated above the lower frame assembly, the second upper frame assembly having a plurality of the gas distribution apertures disposed therein; the first and second upper frame assemblies being shaped and oriented relative to each other to collectively define a ring-like configuration. 